Coal imports to the U.S. are rising sharply even as coal mines close throughout Central Appalachia.

A big reason: price. It costs $26 a ton to ship coal from Central Appalachia to power plants in Florida compared with $15 a ton to get coal from a mine in Colombia, according to research firm IHS Energy.

Labor costs are lower in Colombia, and it's much more cost effective to move coal by ship, which can transport well over...